CPR Overflow help

[rljlll]

i have one i got used never have used it before but decided to try well it wont start to suction i kill the pump right as the water hits the brim of the tank so it doesn't flood any idea or help would be appreciated

[evolust]

Use some airline tuing and suck the air out of the trap or U tube and that starts the flow

[aztbs]

I have never had a CPR, I have only used the U-tube style overflows. But, this may still work. You need to stick a small piece of airline tubing up into the section that goes over the edge of the tank (should be black I think?) Fill both sides of the overflow with water and then suck the air out of the high part. If there is an air bubble in there, you will never get siphon.
Have something handy to spit in when you get a mouthful of tank water. :lol:
Good luck.

[DarkFORCE]

I have a CPR CS102. I use a MaxJet 900 to keep it primed.

[Luvabull]

I have the overflow and you gotta put water in the back part where it pours out, when the water level gets into the overflow front, start sucking. It's nasty. I also bought a pump that drips to constantly suck any air out of the top to keep it flowing good.

[Satori]

You will really need to have some sort of pump to keep the air sucked out constantly. Here's one example:

http://www.marinedepot.com/md_viewItem.asp?idproduct=TA3191

The rio pump just always runs, and the venturi attachment keeps sucking the air out of the overflow.

When I very first got a CPR, I had a piece of airline tubing with a needle valve attached to the "nipple" on the overflow. Twice a day I would open the valve to suck out the air. Twice, the air built up while I wasn't home, the siphon broke, and the place flooded.

One annoying thing about a venturi pump is that it blows air bubbles. I put the rio in the back chamber of the overflow with about 6" of airline tubing, and it never failed.

[rljlll]

ok thanks guys that help a lot but what if the power goes out ill flood wont i if im not there to start the siphon

[aztbs]

The idea on that is to make sure that the return section of the sump hold no more water than the tank can hold without overflowing.

So set the CPR box so that it keeps the water level a bit below the top of the tank. If the siphon breaks, the return pump will put all the water back in the tank until it runs dry because your overflow box is not providing any more water.

At that point, you just have to worry about your pump running dry. The U-tube overflow style never lost siphon. When the power goes out, the water stays in the tube. Once you get it started, it should maintain it. Only testing it out while you are there will say for sure.

[DarkFORCE]

Put little holes just below the water level on the sump returns.

[aztbs]

<a href=showthread.php?s=&postid=7788955#post7788955 target=_blank>Originally posted</a> by DarkFORCE
Put little holes just below the water level on the sump returns.

That covers the opposite situation - where the return pump stops and the water from the overflow/return lines drains back in to the sump. I think he is concerned about the pump still running and the overflow stopping. The main display will flow over if there is enough water in the sump to do so.

[rljlll]

ok ok let me try to explain i just finished setting up my fuge i am running the CPR overflow to return the water back into the sump after it cycles through the fuge i am worried about it flooding the fuge if the siphon doesnt return when the power comes on

does this help

[Satori]

You're fine during a power outage. With no water flowing through the overflow, no air bubbles build up. The siphon lasts indefinitely like that, ready to start again as soon as power is restored.

[Pyrrhus]

If you are really worried get an aqualifter pump and inline filter, problem solved.

[clkwrk]

or buy a reef ready tank........Also if you don't have an overflow thats matched close to your return pump you will need the pump to pull air out. Otherwise the slower flow thru the overflow tube will cause air to build up. I am not a CPR fan.

[Luvabull]

It's not the siphon restarting after a power outage that you need to worry about...it's the back siphon of what is going back into your sump.